SAR-Lupe

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SAR-Lupe is Germany's first reconnaissance satellite system; "Lupe" is German for magnifying glass. It consists of five identical (720kg) satellites and one ground station at the Zentrum für Nachrichtenwesen der Bundeswehr (ZNBw), Max-Planck-Str. 17, 53501 Gelsdorf (50.5683 N, 7.0363 E) which is responsible for controlling the system and analysing the retrieved data. A large data archive of images will be kept in a former Cold War bunker belonging to the ZNBw.

SAR-Lupe Synthetic Aperture Radar (SAR) high-resolution images can be acquired day or night though all weather conditions. The first satellite was launched from Plesetsk at 14:00 GMT on 19 December 2006, about a year after the intended launch date; further satellites will be launched at roughly six-month intervals, and the entire system will be fully operational by 2008.

The five satellites operate in three 500-kilometre orbits in planes roughly sixty degrees apart. They use an X-band radar with a three-metre dish, providing a resolution of about 50 centimetres over a frame size of 5.5km on a side ('spotlight mode', in which the satellite rotates to keep the dish pointed at a single target) or about one metre over a frame size of 8km x 60km ('stripmap mode', in which the satellite maintains a fixed orientation over the earth and the radar image is formed simply by the satellite's motion along its orbit). Response time for imaging of a given area is 10 hours or less.

The testing of SAR-Lupe involved an inverse procedure, in which the satellite, mounted in a radome on Earth, was used to image the International Space Station, whose orbit is reasonably close to the one the satellite will eventually be in. One-metre resolution at the ISS was apparently achieved.

On 30 July 2002 a cooperation treaty between Germany and France was signed, under which the SAR-Lupe satellites and the French Helios optical reconnaissance satellite will operate jointly to form a common European Union (EU) reconnaissance system. Other EU countries have been invited to join as well and Italy has shown considerable interest.